Flame-retardant soundproof material for vehicles

Abstract

A flame-retardant soundproof material for vehicles includes a polyurethane foam obtained by foam-molding a urethane resin composition. The urethane resin composition contains an isocyanate component (A), a polyol component (B), and an expandable graphite (C). The isocyanate component (A) includes a mixture of 2,4′-MDI and 4,4′-MDI, and one or more modified forms selected from carbodiimide modified forms and uretonimine modified forms of at least one of 2,4′-MDI and 4,4′-MDI. The content of the one or more modified forms in the urethane resin composition is 5.0 mass % to 8.8 mass %. The polyol component (B) includes a polyether polyol as a main constituent. The expandable graphite (C) has an expansion initiation temperature of 170° C. to 200° C., an expansion ratio of 10 or more at 250° C., and a content of 8 mass % to 20 mass % in the urethane resin composition.

What is claimed is: 
     
         1 . A flame-retardant soundproof material for vehicles, comprising a polyurethane foam obtained by foam-molding a urethane resin composition, wherein
 the urethane resin composition contains an isocyanate component (A), a polyol component (B), and an expandable graphite (C),   the isocyanate component (A) comprises a mixture of 2,4′-diphenylmethane diisocyanate and 4,4′-diphenylmethane diisocyanate, and one or more modified forms selected from carbodiimide modified forms and uretonimine modified forms of at least one of 2,4′-diphenylmethane diisocyanate and 4,4′-diphenylmethane diisocyanate, wherein a content of the one or more modified forms is 5.0 mass % to 8.8 mass % based on 100 mass % of the entire urethane resin composition,   the polyol component (B) comprises a polyether polyol as a main constituent,   the expandable graphite (C) has an expansion starting temperature of 170° C. to 200° C., an expansion ratio of 10 or more at 250° C., and a content of 8 mass % to 20 mass % based on 100 mass % of the entire urethane resin composition,   a breaking elongation of the polyurethane foam is 70% or more, and   the flame-retardant soundproof material for vehicles has a flame retardancy of V-0 level of UL94 standard in either of a normal condition and a condition after heat aging at 150° C. for 168 hours.   
     
     
         2 . The flame-retardant soundproof material for vehicles of  claim 1 , wherein the expandable graphite (C) consists of particles having a particle size of 250 μm or more by means of sieving. 
     
     
         3 . The flame-retardant soundproof material for vehicles of  claim 1 , wherein the expandable graphite (C) consists of particles having a particle size of 355 μm or more by means of sieving. 
     
     
         4 . The flame-retardant soundproof material for vehicles of  claim 1 , wherein the expandable graphite (C) consists of particles having a particle size of 425 μm or more by means of sieving. 
     
     
         5 . The flame-retardant soundproof material for vehicles of  claim 1 , wherein the expandable graphite (C) has a content of 13.5 mass % or more based on 100 mass % of the entire urethane resin composition is. 
     
     
         6 . The flame-retardant soundproof material for vehicles of  claim 1 , wherein the isocyanate component (A) further comprises a prepolymer obtained by reacting diphenylmethane diisocyanate with a polyol. 
     
     
         7 . The flame-retardant soundproof material for vehicles of  claim 1 , wherein the polyether polyol in the polyol component (B) has a number of functional groups of 2 to 8 and a mass average molecular weight of 1000 to 10000. 
     
     
         8 . The flame-retardant soundproof material for vehicles of  claim 1 , which has a flame retardancy of V-0 level of UL94 standard after heat aging at 150° C. for 336 hours. 
     
     
         9 . The flame-retardant soundproof material for vehicles of  claim 1 , wherein the urethane resin composition does not contain a flame retardant other than the expandable graphite (C).